Field of the Invention
This invention relates generally to the construction of grinding wheels and, in particular, to a new and useful method of making such grinding wheels.
The invention relates particularly to a method of manufacturing a grinding wheel with at least two, preferably more, grinding wheels, always enclosing a non-abrasive, vibration damping layer, preferably of a polymer therebetween, and at least one reinforcing tissue, with a grinding mixture of abrasive grains, a binder, preferably a phenolic resin, and of preferably abrasive and/or non-abrasive filler materials being mixed, placed in a mold, and then cured at temperatures between 150.degree. C. and 200.degree. C.
It is known that while using high speed offhand grinding bodies, annoying excessive noise is produced which is caused by vibrations of the driving machine (transmission, cooling fan), of the grinding wheel, and of the treated workpiece.
The noise is so great that damage to personnel's hearing occurs. Impaired hearing cases of first compensations for occupational illness was 91% in the metal working industry within the period from 1971 to 1980. This also prompted efforts to reduce noise produced during offhand grinding.
German OS's Nos. 2610580 and 2632652 disclose sound-deadened grinding wheels comprising at least one damping layer connected to the grinding layer made of a highly attenuating material; more particularly, they provide a polymer layer having a Shore A hardness of less than 90 and a loss factor of at least 0.25.
The failure of those wheels to prevail in practice was predicated on reasons of economy, namely on the fact that their manufacture was too expensive.
Basically, the mentioned references provide a plurality of individual grinding wheels or discs which have to be manufactured separately and then assembled and cemented together by means of a polymer. The problem then is to apply the polymer uniformly in a manner to prevent it from oozing out in the area of the bore and at the periphery during the subsequent assembly of the grinding disc or individual grinding wheels.